1. Field of the Invention
The present invention relates generally to an instrument panel for a vehicle, and more particularly to the instrument panel which is excellent in impact resistance, heat resistance, fabrication operation efficiency and appearance to meet the requirements of MVSS No. 201 and ECE No. 21.
2. Description of the Prior Art
In connection with vehicular instrument panels, there is a rapidly advanced recent trend in which the instrument panels are made of plastics such as polypropylene composite material or modified polyphenyleneether. This is because plastics are excellent from the viewpoints of strength, variety of designing, decorative design, touch, cost and the like. Of such plastics, polypropylene is particularly excellent in balance of the above viewpoints and therefore has been widely put into practice. However, instrument panels are eagerly required to be improved in quality with diversification of consumers'needs, assertion of personality, and enlarged markets. In concrete, further improvements of instrument panels are required in the areas of impact resistance, heat resistance, fabrication operation efficiency and appearance.
Hitherto, in order to provide higher heat resistance for required product characteristics for an instrument panel made of plastic material including polypropylene as a main component, it has been proposed to blend into the polypropylene plastic material a variety of inorganic fillers such as talc, mica, calcium carbonate and the like. Furthermore, many proposals have been made for producing instrument panels, in which specifying polypropylene plastic material and addition of various rubber components are made to provide higher impact resistance, and specifying polypropylene plastic material and selection of inorganic fillers are made to improve appearance and fabrication operation efficiency.
However, even with such proposals. the above-mentioned various requirements for instrument panels cannot be sufficiently met. In this regard, improvements have been made in which instrument panels are formed of polypropylene plastic material filled with fibrous fillers, particularly glass fiber. However, the thus produced instrument panels are excellent in heat resistance but lower in impact resistance and inferior in fabrication operation efficiency and appearance because of flow mark like a silver streak is formed. As a result, the instrument panels of the glass fiber-filled polypropylene plastic material have design restrictions and unavoidably require many measures such as various strength improvements and appearance improvement, resulting in a considerable increase in production cost. Otherwise, it has also been tried to form instrument panels of materials other than popypropylene plastic material, for example, modified polyphenyleneether; however, this is disadvantageous from view points of fabrication operation efficiency and production cost.